It is well known that domestic electrical appliances incorporating moving parts and/or heating elements that could, under certain operational circumstances, cause harm to a user have interlock systems to protect users by preventing the flow of electric current to the prime mover or heating element when such operational circumstances occur. Thus, interlock systems are an essential feature of many domestic appliances, and their components need to satisfy demanding, and sometimes opposing, regulatory, operational and economic criteria. Hence difficulties arise in providing interlock systems that are sufficiently robust and reliable to meet user demands and comply with stringent regulatory stipulations, whilst being economical to produce and conforming to an acceptable aesthetic design.